Impedance assembly



July 1'9, 1960 R. ABRAMS ET AL IMPEDANCE ASSEMBLY Filed Dec. 22, 1955L.. im m.; W w mma d n am n I www y Bbw f nited States Patent OIMPEDANCE ASSEMBLY Ralph A'brams, Sharon, Danforth W. Comins, Jr., Con`Filed Dec. 22, 195s, ser. No. 554,872

s claims. (c1. 336-136) The present invention relates to tunableimpedance devices of the type having an adjustable core member.

`Objects of the invention are to provide adjustable impedance devices,such as for example coil forms, that are especially suitable forminiature or near miniature embodiments, to provide such devices thatare shock resistant, exceptionally rugged and precise, and yetcomparatively inexpensive, to provide such devices which areelectrically shielded against radiation and therefore especiallysuitable for use in close proximity of other elements in circuits whereadjacent mounting is necessary, to provide such devices which give awidevariety of possibilities of mounting -as well as modification ofelectric characteristics such as type of windings or electrodes, ornumber ofl terminals, and to provide devices of this type which permitpartial assembly at the factory and easy and secure com pletion andmounting with basic tools.

A brief summary of the invention, yindicating its nature and substancefor attaining the above objects, is as follows. A tunable impedancedevice according to a principal aspect of the `invention comprisestubular form means such as a coil form, housing means which have at oneend stud means with mounting means on the outside of a cavity that litsthe form means and which housing means has at the other end shell meansforming a chamber that is wider than the -form means, the form meansextend-ing from the cavity into the shell means with clearance toaccommodate an impedance element such as -a coil and stationary cup coremembers, and means axially penetrating the stud means into the spacewithin the form means, for carrying an internal core member and foraxially adjusting it within the form means. In a preferred embodiment,the shell contains cup core members surrounding a coil on the form meansand elastic spacing members within the shell which are compressed by aterminal board that is yfixed to the open end of the shell with a springring or a cap, which ylatte-r can be provided with a ground tab.

. These and other objects, and aspects of the nature of the inventionwill appear from the herein presented description of several typicalembodiments illustrating its novel characteristics.

The description refers to a `drawing in which Fig l is the top elevationof an assembly according to the present invention with part of thespring ring broken away to show the terminal board key rin Iits shellnotch;

Fig. 2 is a section on lines -2-2 of Fig. l;

Fig. 3 is a section on lines 3-3 of Fig. 2;

Fig. 4 is a section lon lines -4--4 of Fig. 2;

Fig. 5 is a top elevation of the spacer that can be incorporated in theassembly;

` Fig. 6 is a top elevation of the cup core cap incorporated in theassembly;

Fig. 7 is an axial section through the retaining cap of a secondembodiment of the invention; and

Fig.,8 is an axial section similar to Fig. 2, of a second embodiment ofthe invention.

In Figs. 1 to 4, the housing 21 has a shell portion 21.1 and a studportion 21.2. The shell portion has, in the embodiment shown, an annularrecess 21.11 for the retaining spring ring to be described below, and anotch 21.24 for the key 32.7 of the terminal assembly to be describedbelow. The stud portion 21.2 has a cylindrical portion 21.21, threadedon the outside, and a hemispherical portion 21.22which latter isprovided /with a plurality, for example four slits 21.23. Thehemispherical portion 21.22 of the stud portion 21.2 of the housing 21has an axial perforation 21.3 with an inside thread to receive vthespindle 25 of the tuning core.

The chamber of the shell portion 21.1 leads into the `cavity of the studportion by way of a shoulder 21.9.

A form 23, made of insulating material, fits the cavity 21.4 of the studportion 21.2. Within the form 2.3l is slidably inserted a tuning core orslug 24 which is mounted on the above mentioned spindle 25 that isthreaded into the axial hole 21.3 of the hemispherical portion 21.22 ofthe stud portion 21.2 of the housing.

In the present embodiment which represents a tuning reactance, the coreis made of iron powder and has a slot 24.1 for screwing it onto thespindle 25 by means of an inside threaded recess 24.2.

On the form 23 is wound a wire winding 27, indicated by cross-hatchingin Figs. 2 and 3. The winding is surrounded by a cup core 28 and a cupcore cap 29, both made of iron powder material. As indicated in Fig. 2,the cup core cap has a recess 29.1 and a number, such as four, notches29.5, as indicated in Fig. 6. On the cup core cap tits a spacer 31 ofelastic material such as sponge rubber which is also shown in Fig. 5 andwhich has a number, for example four, notches 3.1.1. Between the bottomof the cup core 28 and the shoulder 21.8 is a rubber washer 21.9.

On the spacer 31 lits the terminal board assembly 32 which, as shown inFig. l, has ya number, for example four, terminals 32.1. 'Theseterminals are hollow as indicated at 32.5, permitting a wire to bethreaded therethrough and soldered thereto from the outside thereof.

A retaining spring ring 35 i-s inserted in the recess 21.11 inconventional manner, as indicated in Figs. il and 2.

In this embodiment of the invention, the spindle 2S with slug 24 islixed relatively to the housing 21 by means of a lock nut 25.1'whichserves for tightening the hemispherical portion 21.22 on the spindle 25,by means of the slits 21.23 which reach somewhat into the threadedportion of the spindle region 21.2, the lip 25.2 of the lock' nut 25.1serving to compress the slotted hemispherical .portion 21.22 when thelock nut is tightened. 'Ihe core- 24 is adjusted by means of rotatingthe slotted spindle 25. with a simple tool. position by means oftightening the lock nut \25.11 as above described.

The assembly can be mounted on a support such as a panel indicated atl41 of Fig. 2.,.by means of a lock washer' `42 and a nut 43, likewiseshown in Fig. 2.

The housing 21 is conveniently made from brass, the coil form 23 fromphenolic resin, the spacers `21.9 and 31 from sponge rubber and theterminal board 32 for exam- The above described device is assembled andoperated as follows.

These assemblies are usually shipped from the factor with the tuningcore 24 on the spindle 25 assembled with-V in the housing 21, whereasthe parts that go into the,

shell portion 21.1 are furnished in bulk.

After adjustment, the core is set inl Before completely assembling thedevice, the impedl the lower end ofthe form restingv at thel conicalbottom of the cavity with the washer 21.9. inserted in theA shellV ontthe shoulder 21.8, as indicated in Fig. 2. The upper endy ofthe formextends into the chamber of the shell. portion 21.1. The cup core canthen be filled with irnpregnant as required' according toconventionwtech.- niques;

If it is desired to. pot the coil assembly outside ofthe shell, forexample for the purpose of baking it to properly cure the impregnant,various expedients are feasible, for example the` following' one. Thecoil form with the winding on iti is inserted into the powder metal cupcore by means ofI a jig which has a plurality of raised. portionscorresponding in shape to that of the cup core cap 29, thus properlypositioning the form within the cup. By means of an eye dropper, someadhesive agent such yas available under the trade designation Epoxy isthen applied to the gap between the cup core and the form, andvpermitted to cure. These Epoxy materials, well known at this time, areresin polymers that together with a curing agent such as a catalyst orcross-linking agent set at room temperature within abouty one hour, andcompletely lill a gap due to their surface tension properties. Thesubassembly of form and cup can then be handled in any desirablefashion, and since the gap therebetween is sealed, the impregnant iswith safety confined in the void between the. coil and cup core duringfilling as well as baking.

Care has to be taken in all cases not to allow any of: the impregnatingcompound to become deposited on the inside of the form since this wouldimpair movement of the tuning core. This however is effectivelyprevented by the above described sealing technique or one similarthereto.

No matter how the shell, the coil. form andY the cup core are assembledthe cup core cap 29 is then put on and then the sponge rubber spacer 31,care being taken to orient the coil leads to pass through the notches of29 and 31 (Figs. 5 and 6) and to mate them correctly with the terminalswhenthe terminal assembly 35 is nally put.

on. The core leads are left extending through the cup corey notches atleast one inch; for easy insertion through the terminals. They are thenstripped and tinned to within about one-eighth of an inch of, the cupcore.

The coil leads are threadedv through' the terminals of the terminalboard, through the holes 32.5 indicated in Figs. 1 and 2 and theterminal board is then placed over the spacer 31. The terminal board ispressed down to compress the spacers, and the retaining ring 35 isinserted into the groove 21.11. The bent ends protrude, as shown in Fig.1, through the housing notch 21.24 which also accommodates the key 32.7of the terminal board.

The leads can then be soldered to the terminals in conventional manneror otherwise connected.

It will be evident that the terminal assembly can be furnished with anydesired number of terminals, four being shown in the present embodiment.

The embodiment according to Figs. 7 and 8 is in principle similar tothat abovedescribed, with the following modications.

^ Instead off holding the assembly together by means of a spring ringsuch as component 35 of Figs. 1 and 2, a cap. 51 with slots 51.1 issometimes preferable. This cap is slightly collapsed after slotting sothat it fits snugly on the shell outside diameter. For permanentassembly the cover can be secured to the shellwith a dot of solderindicated at 52 of'Fig. 8. This construction has the advantage that theassembly can be provisionally secured without the use of any toolwhatsoever and can then be permanently fixedA without any danger of a`confining member such as spring 35 becoming detached.

Fig. 8 also indicates a somewhat different embodiment of the form 53,which has in this instance flanges 53.1, 53.2 for better confining awinding, for example of very fine wire. In this instance the cup corecap 59 can be flat on both sides.

Fig. 8 also indicates another mode of fixing the adjustabler core.member 2`4 with` its spindle 25, by means of` a torsion spring ringmember 62 on a neck portion 27 of thestudy portion 61.2 of'v the housing61 with its shell portion 612.1, In this instance the outside threadofthe stud end 61.2Y is-,sornewhat wider than the spring ring 62, sothat a mounting washer 42 and a nut 43 can be inserted over the end ofythe stud portion with the spindle 25 protruding therefrom.

This embodiment lends itself especially well for providing a groundingterminalA for the assembly` as a whole. Forthis` purpose a tab 65 is`stamped from the metal for the cap 51 and bent upwardly as indicated inFig. 8-.

It will now be evident that the above described construction provides afirm and positive support for the form 23, in the cavity 21.4 and at thesame time permits complete withdrawal of the core 24 from the cup core28, 29 thus permitting a wider range of adjustment. It will be furtherapparent that the stud portion 21.2 not only provides the abovementioned cavity forv better securing the form and for fully withdrawingthe adjustable core but also has the function of a mounting member byway of' its outside thread 21.21. This construction thus providesunusually versatile and yet compact and simple construction, due to thistriple function of the stud portion 21.2 of the housing-21.

It will be also apparent that the unobstructed outsideof the chamberportion of the housing shell 21.1 permits the use of a spring ring suchas 35 of Figs. 1 and 2 alternatively with that of a slotted cap as shownin Figs. 7 and 8, since it is possible to use a housing according toFigs. l and 2, provided with the annular recess 21.11, also with a cap51, according to requirements.

It will be further apparent that the assembly according to the presentinvention is unusually well shielded electrically and is particularlywell suited for applications that require miniature size, a rugged andshock resistant construction' and a mechanically enclosed and thusfully' protected coil.

' The construction according to Fig. 8, with a cap 51 having a groundingtab 65, lends itself especially well" for mounting on a printed circuitpanel such as indicated at 40 ofy Pig. 8. In this instance the terminals32 and the tab 65 are inserted into perforations of the panel 40 and theprotruding ends dip soldered thereto in conventional manner. It will beevident that the stud mounting means such as the outside thread of thestud portion, for the washer 42 and the nut 43, can then be omitted.

It should be understood that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claims.

We claim:

l. A tunable impedance ydevice of the type having an adjustable coremember, comprising: smoothly tubular form means; a housing which has atone end stud means with fastening means on the outside and with a`cavityl that lits said form means, and' which housing has at the otherend integrally therewith a chamber that is wider than said form means,said cavity being contracted at the extreme end of the stud means andcommunicating on the opposite end with said chamber with a shoulder,said form` means extending from said cavity into said chamber; in saidchamber a cup-shaped `core with its' bottom resting on said shoulder andhaving in said bottom an opening for said. form means, the clearancebetween said core and Said form means accommodating a Winding; adisk-shaped core cap fitting into the open end of said cup-shaped coreand resting on said form means; loosely inserted into said chamberelastic washer means extending over both core and core gap; meansincluding a terminal board secured to the outer end of said chamber forcompressing and confining said core, core cap, and washer means; andaxially threaded into said extreme end of said stud means andpenetrating into the space within said form means, a spindle forcarrying said core member and for axially adjusting it Within said formmeans; whereby said core means can be substantially fully withdrawn fromthe chamber region of said form means into its stud cavity region, suchas essentially to disassociate said core means from said chamber.

2. A tunable impedance device of the type having an adjustable coremember, comprising: tubular form means; a metal housing which has at oneend'a stud portion with mounting means on the outside and with a cavitysnugly tting said form means along a portion long enough substantiallyto receive said core member and' which housing has at the other end ashell portion integral therewith with a chamber that is wider than saidform means, said cavity being contracted at the extreme end of the studportion and leading on the opposite end of the stud portion with ashoulder into said chamber, and

said form means extending from said cavity into said chamber where ithas a peripheral clearance to accommodate an impedance element; withinsaid chamber a cup shaped iron core member placed with its bottomresting on said shoulder; a' terminal board' member tting the inside ofsaid chamber; resilient plate means arranged adjacent to said cup coremember; means for holding said cup core member, said terminal boardmember and said resilient plate means under compression Within saidchamber; and, attached at said contracted extreme end of said stud meansand extending into the space within said form means, means for carryingsaid core member and for axially adjusting it within said form means;whereby the core means can be substantially fully withdrawn from theshell chamber region of the form means into its stud cavity region, suchas essentially to disassociate the core means from the chamber, and theform means, cup core member, plate means and terminal board member areiirmly and compactly confined within the chamber.

3. Device according to claim 2 wherein said holding means includes anannular recess on the inside of said chamber near the outer rim of theshell portion, and a spring ring inserted therein.

References Cited in the iile of this patent 'UNITED STATES PATENTS Re.22,103 Harvey May 26, 1942 2,130,815 Riepka Sept. 20, 1938 2,482,902Clark Sept. 27, 1949 2,669,700 Rauch Feb. 16, 1954 FOREIGN PATENTS479,880 Great Britain Feb. 14, 1938

